Cadmium affects metabolic responses to prolonged anoxia and reoxygenation in eastern oysters (Crassostrea virginica)

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology Vol. 297; no. 5; pp. R1262 - R1272
• Main Authors: Kurochkin, I. O, Ivanina, A. V, Eilers, S, Downs, C. A, May, L. A, Sokolova, I. M
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.11.2009
• Subjects: Amino Acids - metabolism; Anaerobiosis - physiology; Animals; Cadmium; Cadmium - pharmacology; Cadmium - toxicity; Crassostrea - drug effects; Crassostrea - metabolism; DNA Damage - drug effects; DNA Damage - physiology; Fatty Acids - metabolism; Hemolymph - metabolism; Metabolism; Mitochondria - drug effects; Mitochondria - metabolism; Mollusks; Oxidation; Oxidative Stress - drug effects; Oxidative Stress - physiology; Oxygen; Oxygen - metabolism; Oxygen Consumption - drug effects; Oxygen Consumption - physiology; Oysters; Water Pollutants - pharmacology; Water Pollutants - toxicity
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00324.2009

1 Department of Biology, University of North Carolina at Charlotte, Charlotte, North Carolina; 2 Hochschule Bremen, Bremen, Germany; 3 Haereticus Environmental Laboratory, Clifford, Virginia; 4 JHT, Inc., Contractor for National Oceanic and Atmospheric Administration, National Ocean Service, Center for Coastal Environmental Health and Biomolecular Research, Hollings Marine Laboratory, Charleston, South Carolina Submitted June 9, 2009 ; accepted in final form August 31, 2009 Benthic marine organisms such as mollusks are often exposed to periodic oxygen deficiency (due to the tidal exposure and/or seasonal expansion of the oxygen-deficient dead zones) and pollution by metals [e.g., cadmium, (Cd)]. These stressors can strongly affect mollusks' survival; however, physiological mechanisms of their combined effects are not fully understood. We studied the effects of Cd exposure on metabolic responses to prolonged anoxia and subsequent recovery in anoxia-tolerant intertidal mollusks Crassostrea virginica (eastern oysters). Anoxia led to an onset of anaerobiosis indicated by accumulation of L -alanine, acetate, and succinate. Prolonged anoxia (for 6 days) caused a decline in the maximum activity of electron transport chain and ADP-stimulated ( state 3 ) oxygen uptake by mitochondria (MO 2 ), but no change in the resting ( state 4 ) MO 2 of oyster mitochondria, along with a slight but significant reduction of mitochondrial respiratory control ratio. During reoxygenation, there was a significant overshoot of mitochondrial MO 2 (by up to 70% above the normoxic steady-state values) in control oysters. Mild mitochondrial uncoupling during prolonged shutdown in anoxic tissues and a subsequent strong stimulation of mitochondrial flux during recovery may help to rapidly restore redox status and protect against elevated reactive oxygen species formation in oysters. Exposure to Cd inhibits anaerobic metabolism, abolishes reoxygenation-induced stimulation of mitochondrial MO 2 , and leads to oxidative stress (indicated by accumulation of DNA lesions) and a loss of mitochondrial capacity during postanoxic recovery. This may result in increased sensitivity to intermittent hypoxia and anoxia in Cd-exposed mollusks and will have implications for their survival in polluted estuaries and coastal zones. air exposure; recovery; mitochondrial function; oxidative damage; mollusks Address for reprint requests and other correspondence: I. M. Sokolova, Dept. of Biology, Univ. of North Carolina at Charlotte, 9201 Univ. City Blvd., Charlotte, NC 28223 (e-mail: isokolov{at}uncc.edu ).